# US 5,349,824 A · Process for the mixed production of high and low purity oxygen

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- Number: US 5,349,824 A
- Document ID: US5349824A
- Status: Granted
- Kind: A
- Application number: 08/083,515
- Filed: 1993-06-30
- Granted: 1994-09-27
- Earliest claimed: 1991-10-15
- Assignees: Liquid Air Engineering Corporation
- Inventors: Bao Ha; Catherine Garnier
- Web page: https://patentgrep.com/patent/US5349824A

## CPC

- F25J 3/0409: {of oxygen}
- B01D 3/322: {Reboiler specifications}
- F25J 3/04175: {at a pressure of substantially more than the highest pressure column}
- F25J 3/04206: {including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product}
- F25J 3/04296: {Claude expansion, i.e. expanded into the main or high pressure column}
- F25J 3/04418: {with thermally overlapping high and low pressure columns}
- F25J 2200/54: in the low pressure column of a double pressure main column system
- F25J 2215/52: Oxygen production with multiple purity O2
- F25J 2250/40: One fluid being air
- F25J 2250/50: One fluid being oxygen
- Y10S 62/924: Argon
- Y10S 62/94: High pressure column
- F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An apparatus for simultaneously producing both high and low purity oxygen, which contains a double rectification column having therein a lower pressure fractionating column with two reboilers therein, and a higher pressure fractionating column, wherein an intermediate outlet is provided between the two reboilers of the lower pressure fractionating column for extracting a lower purity oxygen stream therefrom, and a high purity liquid oxygen stream from a bottom portion of the column simultaneously.

## Claims

### Claim 1

A process for simultaneously producing both high and low purity oxygen from a double column, double reboiler apparatus, the double columns being low and high pressure columns, and said low pressure column having a lower and an upper reboiler, which comprises:
a) condensing a first compressed and cooled feed stream fraction containing at least nitrogen and oxygen in a reboiler located at the bottom of the lower pressure column;
b) feeding at least a fraction of the resulting liquefied feed stream to either high or low pressure columns or both as feed;
c) introducing a second fraction of a feed stream to a bottom of the high pressure column as gaseous feed, whereby a bottom oxygen-rich liquid stream and an overhead nitrogen-rich gaseous stream are formed;
d) passing the oxygen-rich liquid stream to the low pressure column as feed;
e) condensing the nitrogen-rich gaseous stream against a boiling liquid in an upper reboiler of the low pressure column, thereby serving as a second reboil for distillation;
f) returning a portion of the condensed nitrogen-rich stream to the high pressure column as reflux, and passing at least a fraction of a remaining portion of the nitrogen-rich stream to the top of the low pressure column as reflux, whereby the low pressure column separates its feeds into bottom stream oxygen product and top stream-rich in nitrogen;
g) recovering the bottom stream oxygen product as high purity liquid oxygen; and
h) drawing from a tray or a stage between the two reboilers of the low pressure column, an oxygen product stream as low purity oxygen.

### Claim 2 (depends on 1)

The process of claim 1, wherein the feed stream further contains argon.

### Claim 3 (depends on 2)

The process of claim 2, wherein the feed stream is atmospheric air.

### Claim 4 (depends on 3)

The process of claim 3, which further comprises recovering argon by means of an argon side arm column and a tray or a stage between the two oxygen product outlets.

### Claim 5 (depends on 1)

The process of claim 1, wherein in step a) the feed stream is compressed to a pressure of about 6 to 50 bar.

### Claim 6 (depends on 5)

The process of claim 5, wherein the feed stream is compressed to a pressure of about 10 to 35 bar.